Anne Becker

Gut microbiota affects sensitivity to acute DSS-induced colitis independently of host genotype.

Abstract:Caspase-deficient mice and wild-type (WT) mice show significant differences in their gut microbiota composition. These differences coincide with the observation that caspase-3–deficient mice carrying a natural caspase-11 mutation (Casp3/11−/−) are less sensitive to acute dextran sodium sulfate-induced colitis than WT mice. For these reasons, we investigated the role of the microbiota in the development of colitis by cohousing WT and Casp3/11−/− mice. Microbial community fingerprinting by denaturing gradient gel electrophoresis analysis revealed that the similarities in gut microbial composition of WT and Casp3/11−/− mice increased after cohousing. In the acute dextran sodium sulfate-induced colitis model, Casp3/11−/− mice that were cohoused with WT mice showed increased weight loss and disease activity scores and increased neutrophil infiltration and inflammatory cytokine levels in their colon tissue compared with Casp3/11−/− mice that were not cohoused with WT mice. Also, we demonstrate that only the microbiota of the Casp3/11−/− mice cohoused with WT mice showed an important increase in Prevotella species. In conclusion, our cohousing experiments revealed that the colitogenic activity of the WT microbiota is transferable to Casp3/11−/− mice and that Prevotella species are likely to be involved. By contrast, the relative protection of Casp3/11−/− mice against dextran sodium sulfate damage is not transferred to WT mice after cohousing. These results underscore the need for in-depth studies of the bilateral interaction of host genes and microbiota to gain insight into the mechanisms of disease pathogenesis. Our findings also have important implications for the experimental design of disease studies in genetically modified mice and conclusions drawn from them.

Phylogenetic analysis of faecal microbiota from captive cheetahs reveals underrepresentation of Bacteroidetes and Bifidobacteriaceae

BackgroundImbalanced feeding regimes may initiate gastrointestinal and metabolic diseases in endangered felids kept in captivity such as cheetahs. Given the crucial role of the host’s intestinal microbiota in feed fermentation and health maintenance, a better understanding of the cheetah’s intestinal ecosystem is essential for improvement of current feeding strategies. We determined the phylogenetic diversity of the faecal microbiota of the only two cheetahs housed in an EAZA associated zoo in Flanders, Belgium, to gain first insights in the relative distribution, identity and potential role of the major community members.ResultsTaxonomic analysis of 16S rRNA gene clone libraries (702 clones) revealed a microbiota dominated by Firmicutes (94.7%), followed by a minority of Actinobacteria (4.3%), Proteobacteria (0.4%) and Fusobacteria (0.6%). In the Firmicutes, the majority of the phylotypes within the Clostridiales were assigned to Clostridium clusters XIVa (43%), XI (38%) and I (13%). Members of the Bacteroidetes phylum and Bifidobacteriaceae, two groups that can positively contribute in maintaining intestinal homeostasis, were absent in the clone libraries and detected in only marginal to low levels in real-time PCR analyses.ConclusionsThis marked underrepresentation is in contrast to data previously reported in domestic cats where Bacteroidetes and Bifidobacteriaceae are common residents of the faecal microbiota. Next to methodological differences, these findings may also reflect the apparent differences in dietary habits of both felid species. Thus, our results question the role of the domestic cat as the best available model for nutritional intervention studies in endangered exotic felids.

Integrated community profiling indicates long-term temporal stability of the predominant faecal microbiota in captive cheetahs.

Understanding the symbiotic relationship between gut microbes and their animal host requires characterization of the core microbiota across populations and in time. Especially in captive populations of endangered wildlife species such as the cheetah (Acinonyx jubatus), this knowledge is a key element to enhance feeding strategies and reduce gastrointestinal disorders. In order to investigate the temporal stability of the intestinal microbiota in cheetahs under human care, we conducted a longitudinal study over a 3-year period with bimonthly faecal sampling of 5 cheetahs housed in two European zoos. For this purpose, an integrated 16S rRNA DGGE-clone library approach was used in combination with a series of real-time PCR assays. Our findings disclosed a stable faecal microbiota, beyond intestinal community variations that were detected between zoo sample sets or between animals. The core of this microbiota was dominated by members of Clostridium clusters I, XI and XIVa, with mean concentrations ranging from 7.5-9.2 log10 CFU/g faeces and with significant positive correlations between these clusters (P<0.05), and by Lactobacillaceae. Moving window analysis of DGGE profiles revealed 23.3-25.6% change between consecutive samples for four of the cheetahs. The fifth animal in the study suffered from intermediate episodes of vomiting and diarrhea during the monitoring period and exhibited remarkably more change (39.4%). This observation may reflect the temporary impact of perturbations such as the animal’s compromised health, antibiotic administration or a combination thereof, which temporarily altered the relative proportions of Clostridium clusters I and XIVa. In conclusion, this first long-term monitoring study of the faecal microbiota in feline strict carnivores not only reveals a remarkable compositional stability of this ecosystem, but also shows a qualitative and quantitative similarity in a defined set of faecal bacterial lineages across the five animals under study that may typify the core phylogenetic microbiome of cheetahs.